A Fundamental Foundation

Developing a big aerobic base

Slowly and persistently. The key is to accumulate mileage over the course of months and years. Most distance runners should include two blocks of base training in their annual running plan. The minimum period required to obtain a significant improvement in your aerobic base is about six to eight weeks.

If you live in a part of the U.S. where you can train consistently through the winter, then starting aerobic base building in January provides about 12 weeks of solid training before the spring racing season kicks in. Similarly, if you can stand the heat, the relatively quiet racing months of July and August can be a good time for six to eight weeks of base work. With two solid blocks of base training per year, on top of your otherwise "normal" mileage, your aerobic base should build steadily from year to year.

How much and how quickly you should try to increase your mileage depends on your propensity for injury. Although you can increase your mileage dramatically over several years, increasing too much at once is almost certain to leave you injured. As a general guideline, most runners can handle an increase in mileage of 10 to 15 percent every two to three weeks. For example, if you have been running 40 miles per week, you would increase to 44–46 miles for two to three weeks before increasing your mileage again. No rule of thumb works for every runner, however, so you need to pay close attention to your body’s feedback to find the optimal formula.

During your base training, you should avoid VO2-max sessions and speed work and slightly reduce the overall intensity of your training. By backing off the intensity, you can increase your mileage without increasing the overall strain of training. When you are building up your mileage, it is particularly important to train on soft surfaces to reduce the accumulated jarring on your body, and to be sure that your running shoes are in good repair.

Aerobic cross-training, such as cycling, swimming, elliptical training, and deep-water running can contribute to your aerobic base with less risk of injury than further increasing your mileage. The more similar the cross-training activity is to running, the greater the crossover effects will be. If you have a history of injury or live where the winter (or summer) is not conducive to high mileage training, then cross-training can be a worthwhile component of your aerobic base training.